Use element id's for animations

cc/trees/property_tree.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stddef.h>
 
 #include <set>
 #include <vector>
 
 #include "base/logging.h"
@@ skipping 590 matching lines @@
     : scrollable(false),
       main_thread_scrolling_reasons(
           MainThreadScrollingReason::kNotScrollingOnMain),
       contains_non_fast_scrollable_region(false),
       max_scroll_offset_affected_by_page_scale(false),
       is_inner_viewport_scroll_layer(false),
       is_outer_viewport_scroll_layer(false),
       should_flatten(false),
       user_scrollable_horizontal(false),
       user_scrollable_vertical(false),
-      element_id(0),
       transform_id(0),
       num_drawn_descendants(0) {}
 
 ScrollNodeData::ScrollNodeData(const ScrollNodeData& other) = default;
 
 bool ScrollNodeData::operator==(const ScrollNodeData& other) const {
   return scrollable == other.scrollable &&
          main_thread_scrolling_reasons == other.main_thread_scrolling_reasons &&
          contains_non_fast_scrollable_region ==
              other.contains_non_fast_scrollable_region &&
@@ skipping 24 matching lines @@
   SizeToProto(bounds, data->mutable_bounds());
   data->set_max_scroll_offset_affected_by_page_scale(
       max_scroll_offset_affected_by_page_scale);
   data->set_is_inner_viewport_scroll_layer(is_inner_viewport_scroll_layer);
   data->set_is_outer_viewport_scroll_layer(is_outer_viewport_scroll_layer);
   Vector2dFToProto(offset_to_transform_parent,
                    data->mutable_offset_to_transform_parent());
   data->set_should_flatten(should_flatten);
   data->set_user_scrollable_horizontal(user_scrollable_horizontal);
   data->set_user_scrollable_vertical(user_scrollable_vertical);
-  data->set_element_id(element_id);
+  element_id.ToProtobuf(data->mutable_element_id());
   data->set_transform_id(transform_id);
 }
 
 void ScrollNodeData::FromProtobuf(const proto::TreeNode& proto) {
   DCHECK(proto.has_scroll_node_data());
   const proto::ScrollNodeData& data = proto.scroll_node_data();
 
   scrollable = data.scrollable();
   main_thread_scrolling_reasons = data.main_thread_scrolling_reasons();
   contains_non_fast_scrollable_region =
       data.contains_non_fast_scrollable_region();
   scroll_clip_layer_bounds = ProtoToSize(data.scroll_clip_layer_bounds());
   bounds = ProtoToSize(data.bounds());
   max_scroll_offset_affected_by_page_scale =
       data.max_scroll_offset_affected_by_page_scale();
   is_inner_viewport_scroll_layer = data.is_inner_viewport_scroll_layer();
   is_outer_viewport_scroll_layer = data.is_outer_viewport_scroll_layer();
   offset_to_transform_parent =
       ProtoToVector2dF(data.offset_to_transform_parent());
   should_flatten = data.should_flatten();
   user_scrollable_horizontal = data.user_scrollable_horizontal();
   user_scrollable_vertical = data.user_scrollable_vertical();
-  element_id = data.element_id();
+  element_id.FromProtobuf(data.element_id());
   transform_id = data.transform_id();
 }
 
 void ScrollNodeData::AsValueInto(base::trace_event::TracedValue* value) const {
   value->SetBoolean("scrollable", scrollable);
   MathUtil::AddToTracedValue("scroll_clip_layer_bounds",
                              scroll_clip_layer_bounds, value);
   MathUtil::AddToTracedValue("bounds", bounds, value);
   MathUtil::AddToTracedValue("offset_to_transform_parent",
                              offset_to_transform_parent, value);
   value->SetBoolean("should_flatten", should_flatten);
   value->SetBoolean("user_scrollable_horizontal", user_scrollable_horizontal);
   value->SetBoolean("user_scrollable_vertical", user_scrollable_vertical);
-  value->SetInteger("element_id", element_id);
+
+  element_id.AddToTracedValue(value);
   value->SetInteger("transform_id", transform_id);
 }
 
 void TransformTree::clear() {
   PropertyTree<TransformNode>::clear();
 
   nodes_affected_by_inner_viewport_bounds_delta_.clear();
   nodes_affected_by_outer_viewport_bounds_delta_.clear();
 }
 
@@ skipping 1524 matching lines @@
   value->EndDictionary();
 
   value->BeginDictionary("scroll_tree");
   scroll_tree.AsValueInto(value.get());
   value->EndDictionary();
 
   return value;
 }
 
 }  // namespace cc